Department of Zoology, Pachaiyappa's College, Chennai-600 030, India.
The histomorphology of the Interrenal (IR) of Mystus gulio showed hypertrophic changes 24 hours after the last injection of varying dosages of Synthetic Salmon Calcitonin (SCT). The hypertrophic symptoms were increase in the size of the cells and nuclei and lighter staining of the cytoplasm due to depletion of secretory granules. The nucleoli appeared conspicuous, suggesting increased synthetic activity. These changes in the IR might be a direct effect of the alterations in the calcium concentration in blood or a result of the dearth of ovarian hormones consequent to ovarian atrophy.